The invention relates to improvements in vibration damping apparatus, and more particularly to improvements in apparatus which can be used to damp torsional vibrations in the power trains between the engines and transmissions of motor vehicles. Still more particularly, the invention relates to improvements in torsional vibration damping apparatus of the type wherein a composite flywheel comprises several components which are rotatable relative to each other, wherein at least one antifriction bearing is interposed between such components, wherein one of the components is connectable to the engine and another component is connectable with the transmission, wherein one of the components defines an annular chamber for a supply of viscous fluid medium and wherein such chamber contains at least one damper which yieldably opposes rotation of the components of the composite flywheel relative to each other. As a rule, or in many instances, the second component is connectable with the input element of a change-speed transmission by a clutch, such as a friction clutch.
A drawback of presently known vibration damping apparatus of the above outlined character is their high initial and assembly cost. Moreover, the fluid medium is admitted into the chamber through specially provided inlets which must be properly sealed upon completed introduction of a requisite quantity of fluid medium. This also contributes to the initial cost of the apparatus and is a potential source of leakage when the apparatus is in actual use. Another drawback of such conventional apparatus is that sealing of the chamber for the supply of viscous medium from the atmosphere presents serious problems and is normally accomplished by employing a large number of complex and expensive sealing devices.